A bone mineral density test uses X-rays to measure the amount of minerals — namely calcium — in your bones. This test is important for people who are at risk for osteoporosis, especially women and older adults.

The test is also referred to as dual energy X-ray absorptiometry (DXA). It is an important test for osteoporosis, which is the most common type of bone disease. Osteoporosis causes your bone tissue to become thin and frail over time and leads to disabling fractures.